FIG. 1 illustrates a known control device of a non-stage transmission according to a prior art. This known control device was disclosed in Japanese Laid-Open Patent Publication (unexamined) No. 55-65755.
In FIG. 1, numeral 1 indicates an input shaft; numerals 2, 3 indicate pulleys of the input shaft (primary pulleys); numeral 5 indicates a cylinder having a cylinder chamber 4; numeral 6 indicates a pipe line; numeral 7 indicates an output shaft; numerals 8, 9 indicate pulleys of the output shaft (secondary pulleys); 10 indicates a cylinder; 11 indicates a piston; 12 indicates a cylinder chamber; 13 indicates a pipe line; 14 indicates a belt; 15 indicates a pump serving as a hydraulic power source; 16 indicates a tank; 17 indicates a transmission gear ratio detecting shaft; 18 indicates a sensor shoe; 19 indicates a filter; 20 indicates a transmission control valve; 21 indicates a pilot sleeve, 22 indicates a pitot pressure space; 23 indicates an annular groove; 24 indicates an opening; 25 indicates a Pitot tube; 26 indicates a pipe line; 27 indicates a spring; 28 indicates an actuating member; 29 indicates a spring; 31 indicates a throttle cam; 32 indicates a pivot; and 33 indicates a cam follower. Numeral 40 indicates a secondary hydraulic control valve; 41, 42 indicates sleeves; 43 indicates a space; 44, 45 indicate pipe lines; 46 indicates a pitot pressure space; 47 indicates a spring; 50 indicates a pivot; 51 indicates a lever; 61 indicates a pivot; and 62 indicates a turning member.
In the conventional control device of above construction, the primary oil pressure is controlled in accordance with a required transmission pattern from the throttle cam 31 and an engine speed given from the Pitot tube 25 by way of the input shaft 1. On the other hand, the secondary cylinder oil pressure is controlled by detecting a transmission gear ratio by the transmission gear ratio detecting shaft 17, and the secondary oil pressure is reduced with the transmission gear ratio. Then, the pilot sleeve 21 moves to change pipe line according to the primary and secondary oil pressures, whereby the input shaft pulley 3 and the output shaft pulley 9 move to change the transmission gear ratio to non-stage.
FIG. 2 (a) is a diagram illustrating a relation between cylinder pressure, i.e., engine speed ne and the primary cylinder pressure P.sub.1 and secondary cylinder pressure P.sub.2. FIG. 2 (b) is a diagram illustrating a relation between transmission characteristic, i.e., engine speed deviation .DELTA.ne and transmission gear ratio R. FIG. 2 (c) is a diagram illustrating a relation between engine characteristic, i.e., engine speed ne and engine torque .tau.e.
In the above conventional device, however, it was not easy to achieve such a driving performance as allowing improvement in fuel combustion and feeling in accordance with the transmission pattern supplied from the throttle cam 31. Change of driving performance according to type of vehicle was not easy, either. It was impossible to accurately detect engine speed because the Pitot tube 25, serving as an engine speed detector, was mechanically arranged. Accuracy of the transmission gear ratio detecting mechanism was not achieved due to life or secular change. It was impossible to separately control each cylinder oil pressure P.sub.1, P.sub.2. It was also impossible to control the cylinder oil pressures P.sub.1, P.sub.2 according to the intensity of engine torque.
The present invention was made to solve the above problems and has an object of providing a control device of a non-stage transmission in which driving performance can be improved without deviation due to life or secular change, and the primary and secondary cylinder oil pressures can be separately controlled.